public class MyData
    {
        public string Caption { get; set; }
        public List<Data1> ListData1 {get; set;}
    }
 
    public class Data1
    {
        public string FirstName { get; set; }
        public List<Data2> ListData2 { get; set; }
    }
 
    public class Data2
    {
        public string LastName { get; set; }
    }

<DataTemplate x:Key="ItemTemplate">
            <Grid>
                <Grid.ColumnDefinitions>
                    <ColumnDefinition />
                    <ColumnDefinition />
                    <ColumnDefinition />
                </Grid.ColumnDefinitions>
 
                <!--  MyData  -->
                <Grid Grid.Column="0">
 
                    <Grid.RowDefinitions>
                        <RowDefinition />
                    </Grid.RowDefinitions>
 
                    <TextBlock Grid.Row="0" Text="{Binding Caption}" />
 
                </Grid>
 
                <!--  Data1  -->
                <ListBox 
                         Grid.Column="1"
                         DisplayMemberPath = "FirstName"
                         ItemsSource="{Binding ListData1 }" />
                <!--  -->        
 
                <!--  Data2  -->
                <ListBox x:Name="lbData2"
                         Grid.Column="2"
                         DisplayMemberPath = "LastName"
                         ItemsSource="{Binding ????}" />
 
            </Grid>
        </DataTemplate>